Recently, along with a demand for reduction in cost and downsizing of electronic equipment, a downsized power MOSFET has been requested. As such a power MOSFET, there has been proposed a power MOSFET which electrically connects a source electrode and a source region through a metal plug to each other (a power MOSFET 900 relating to a Background Art, see FIG. 22, see patent literature 1 with respect to a semiconductor device which uses a metal plug, for example).
The power MOSFET 900 relating to Background Art includes: a semiconductor base body 910 having a low resistance semiconductor layer 912, a drift layer 914 formed on the low resistance semiconductor layer 912, p-type base regions 918 formed on a surface of the drift layer 914, and source regions 920 which are formed on a surface of the base regions 918; a plurality of trenches 922 formed such that the trenches 922 penetrate the base regions 918 and extend to a depth position where the trenches 922 reach the drift layer 914, and have respective portions of the source regions 920 exposed to inner peripheral surfaces of trenches 922; gate insulation films 924 formed on the inner peripheral surfaces of the trenches 922; gate electrodes 926 embedded in the trenches 922 by way of the gate insulation films 924; an interlayer insulation film 928 covering the base regions 918, the source regions 920, the gate insulation films 924 and the gate electrodes 926; contact holes 930 formed such that one contact hole 930 is disposed between each two trenches 922 disposed adjacently to each other, penetrates the interlayer insulation film 928 and reaches at least the base region 918; metal plugs 932 formed by filling the inside of the contact holes 930 with metal; a source electrode 936 formed on the interlayer insulation film 928 and electrically connected to the base regions 918 and the source regions 920 through the metal plugs 932; and a drain electrode 938 formed on a surface of the low resistance semiconductor layer 912.
The semiconductor base body 910 is brought into contact with bottom surfaces of the metal plugs 932, is electrically connected with the source electrode 936 through the metal plugs 932, and further has p+-type high concentration diffusion regions 934 having higher dopant concentration than the base regions 918.
The power MOSFET 900 relating to Background Art includes: the contact holes 930 formed such that the contact holes 930 penetrate the interlayer insulation film 928 and reach at least the base regions 918; and the metal plugs 932 formed by filling the inside of the contact holes 930 with metal. Accordingly, unlike a power semiconductor device where a source electrode 936 and source regions 920 are directly brought into contact with each other, it is unnecessary to form contact holes having a large diameter and hence, it is possible to provide a downsized power MOSFET. As a result, the power MOSFET 900 relating to Background Art becomes a power MOSFET which satisfies a demand for reduction in cost and downsizing of electronic equipment.